High-frequency migraine headaches, which occur at least 10 days a month, are more common in women during thetransition to menopause, according to a new study.

“For years women have been telling me as a headache doctor that their headaches worsen in perimenopause,” but it hadn’t been directly studied, said lead author Dr. Vincent T. Martin of the University of Cincinnati College of Medicine and co-director of the Headache and Facial Pain Program at the UC Neuroscience Institute.

Symptoms like hot flashes, irritability,insomnia and depression may start during the hormonal changes of perimenopause, when periods become irregular, but menopause does not officially begin until periods have stopped for one year.

“Since the average age of menopause is 51 to 52, and the average transition is five to 10 years, women may see a worsening of their migraines as early as 42 to 47 years old if they are going to have an average-age menopause,” said North American Menopause Society executive director Dr. JoAnn V. Pinkerton. “The variability for normal menopause is 45 to 55, so women could see an intensification before or after that time.”

Changes in brain chemicals may cause blood vessels to swell or dilate, putting pressure on nearby nerves and structures and causing a migraine, Pinkerton told Reuters Health by email.

“Hormonal fluctuations appear to act astriggers for migraines, although the actual mechanism is not known,” said Pinkerton, who was not part of the new study.